The invention relates to an apparatus for transmitting location based messages from vehicles to a stationary infrastructure, comprising at least one transponder mounted on a vehicle, and at least one stationary base in the form of a transceiver for exchanging signals with the transponder.
In public local traffic there is frequently a need to transmit messages from the vehicles to a stationary infrastructure. As examples, the transmission of point actuating commands from trams to a point adjusting device or the transmission of priority requests from busses or emergency vehicles to a traffic light system may be mentioned. These commands and requests are location based in the sense that they are admissible only when the corresponding vehicle is present at a certain location or within a certain area.
Conventional apparatus of this type use transponders and transceivers that have only a very short range. For rail vehicles, the transceiver is typically installed within the track, whereas the associated transponder is mounted in the vicinity of the bottom of the vehicle. Then, communication is possible only at the moment at which the vehicle passes over the transceiver. In this way, it is assured that the point actuating command, for example, can only be issued when the vehicle is found at the specified location.